On Monday, SpaceX made space history, as four astronauts were launched into a pole-to-pole orbit not traveled by any human before them. But why is this orbit so unusual, and why has nobody done it before?
Though the Fram2 mission is a private one on behalf of cryptocurrency billionaire Chun Wang, the crew has a few scientific tasks.
“During their multi-day mission, Dragon and the crew will explore Earth from a polar orbit and fly over Earth’s polar regions for the first time,” SpaceX explains. “They will also conduct 22 research [experiments] designed to help advance humanity’s capabilities for long-duration space exploration and understanding of human health in space. Throughout Fram2’s time on-orbit, the crew are planning to take the first X-ray in space, perform exercise studies to maintain muscle and skeletal mass, and grow mushrooms in microgravity.”
The crew spent their initial time in space getting used to weightlessness.
“The first few hours in microgravity weren’t exactly comfortable. Space motion sickness hit all of us—we felt nauseous and ended up vomiting a couple of times. It felt different from motion sickness in a car or at sea. You could still read on your iPad without making it worse. But even a small sip of water could upset your stomach and trigger vomiting,” Chun Wang wrote on X.
“[Pilot Rabea Rogge] spent some time on the ham radio, making contact with Berlin. No one asked opening the cupola on the first day—we were all focused on managing the motion sickness. We had a movie night watching our own launch and went to sleep a bit earlier than scheduled. We all slept really well.”
Following that sleep, the crew was able to perform a few tasks, including taking the first X-rays in space.
The main “first” of this mission was that they were the first people to orbit around the planet’s poles. No other human has done this, instead orbiting along or near the equator, though for some satellites the polar orbit is beneficial.
“Polar orbits are a type of low Earth orbit, typically between 200 to 1000 km in altitude. Satellites in polar orbits usually travel around Earth from, roughly, one pole to the other, rather than from west to east. They do not need to pass exactly over the North and South Poles; a deviation of 10 degrees is still classed as a polar orbit,” the European Space Agency (ESA) explains.
“Polar orbits are particularly useful for global Earth coverage, as satellites orbiting ‘up’ and ‘down’ Earth’s surface can see every inch of the planet over time as it also rotates below.”
On top of this, there are Sun synchronous orbits, where satellites match Earth’s rotation around the Sun, passing over the same location (e.g. Slough) at the same time every day. This can help if, for example, you want to monitor the change to a specific region of Earth over time.
NASA and other space agencies avoid polar orbits for humans for a number of reasons, including the increased risk to astronaut health posed by flying over the poles, and the added radiation that involves. But the main reason they don’t launch astronauts on this trajectory is economics, and the Earth’s rotation.
The Earth is spinning at around 1,600 kilometers per hour (1,000 miles per hour) at the equator. By launching west to east, as most are, you inherit this motion of the Earth and need less of an additional push to escape Earth’s gravity and achieve orbit.
“This ground speed decreases as one moves away from the equator to the north or south,” Mike Gruntman, professor of astronautics at the University of Southern California, explained to Gizmodo. “The ground speed of the rocket launch location thus contributes to the final velocity of a space vehicle when launched in the eastern direction and thus less propellant is needed and the launch rocket is smaller.”
Launching into a pole-to-pole orbit, you lose this speed boost and have to rely more on expensive propellant to achieve orbit.
Having become the first humans to travel on this unusual orbit, the crew is expected to stay in space for 3-5 days before returning home.
“After safely returning to Earth, the crew plans to exit from the Dragon spacecraft without additional medical and operational assistance,” SpaceX adds, “helping researchers characterize the ability of astronauts to perform unassisted functional tasks after short and long durations in space.”
Source Link: SpaceX Makes History By Orbiting Over The Earth's Poles. Why Haven't We Done It Before?
